Does anyone know if I need to use friction modifier with this oil. This will be the first time I use it.

I have always used Mopar and friction modifier.

On the Valvoline bottle under 75W-140 Gear oil it says; "Limited Slip", does that mean I don't need the friction Modifier? There is no place on the bottle that says anything about it.

One more question; how often do you guys change your rear diff. oil? I carry a very heavy camper and tow at the same time, so I use the schedule B maintenance, every 15,000 miles. The gearbox is always spotless inside when I change oil at 15,000.
I do the tranny oil and filter at 15,000 also and it's also spotless.

I appreciate any help.

 

I just checked their website, and it says the synpower stuff you got contains additives to get rid of "chattering" in a limited slip. In other words, its got friction modifier in it, so you should be all set. I say change it, take it for a testdrive and if it chatters at all, pick up some friction modifier and keep adding a little at a time until the chattering stops.
Changing your rearend lube every 15,000miles seems way to soon, even with heavy towing. I know that in the Hinos we sell at work, they don't have you change it until 100,000miles. I don't know if I'd go that long on yours, but 15,000 seems to soon.
If your tranny is an automatic, and you tow heavy, often, I'd say every 15,000miles can't hurt. It might be to soon, but I'd say in an automatic, sooner is better than later.

 

I use the same oil. I did experience some chatter occasionally after changing the oil so I added 1 small bottle (I got from the dealer) and the chatter went away. The dealer recommended adding 2 bottles but 1 fixed the issue for me.

 

Thanks Tractor Truck, I actually just changed the oil today, I drove it a little this evening and did some tight turns and didn't get any chatter, I have some friction modifier on hand in case it does, so I'll keep an ear tuned in.
The Valvoline cost me $11.50 per Qt. compared to the Mopar at $26 per Qt plus $8.50 per bottle for the F.M. It's hard to believe the difference in cost.

I also found Mopar ATF+4 at Wally World for $4.42 compared to $8 at the dealer.

 

Im pretty sure Valvoline makes the Mopar gear lube... They make Mopar ATF+4 for chrysler.